The present invention relates to articles and methods for imparting softening and anti-static benefits to fabrics in an automatic laundry dryer. More specifically, damp fabrics are commingled with a softening composition containing cationic fabric softener and a "lanolin alcohol" component in an automatic clothes dryer to provide a soft, anti-static finish concurrently with the drying operation. The softening compositions herein are employed in combination with a dispensing means adapted for use in an automatic dryer. The lanolin alcohol component not only provides fabric softening, but also serves to improve release of the softening composition from certain types of dryer dispensing means. Furthermore, the lanolin alcohol component, when used in combination with the cationic fabric softening agents herein reduce the tendency which said cationic materials have to stain fabrics and to cause metal corrosion and/or paint softening in laundry dryers.
Fabric "softness" is an expression well defined in the art and is usually understood to be that quality of the treated fabric whereby its handle or texture is smooth, pliable and fluffy to the touch. Various chemical compounds have long been known to possess the ability to soften fabrics when applied to them during a laundering operation.
Fabric softness also connotes the absence of static "cling" in the fabrics, and the commonly used cationic fabric softeners desirably provide both softening and anti-static benefits when applied to fabrics. Indeed, with fabrics such as nylon and polyester, the user is more able to perceive and appreciate an anti-static benefit than a true softening benefit.
Fatty alkyl cationic anti-static softening compounds and compositions designed for application to fabrics in an automatic dryer have been the subject of recent innovations. (See, for example, Furgal, U.S. Pat. No. 3,634,947, issued Jan. 18, 1972; Morton, U.S. Pat. No. 3,686,025, issued Aug. 22, 1972 and Gaiser, U.S. Pat. No. 3,442,692, issued May 6, 1969.) Other fatty materials have been suggested for use as dryer-added fabric softeners (See, for example, Hewitt et al, U.S. Pat. No. 3,676,199, issued July 11, 1972 and the co-pending application of Murphy and Habermehl, Ser. No. 417,329, filed Nov. 19, 1973, now U.S. Pat. No. 4,000,340, issued Dec. 28, 1976). Included among these prior softening compositions are various glycerides in combination with oil-soluble, lower-ethoxylated surfactants. Glyceride fabric treating agents are disclosed in Bernholz et al, U.S. Pat. No. 3,785,973, issued Jan. 15, 1974; Grimm U.S. Pat. No. 3,896,033, issued July 22, 1975; copending application Ser. No. 440,931, Murphy et al., filed Feb. 8, 1974; and U.S. Pat. No. 4,000,340, Murphy et al., issued Dec. 28, 1976.
As pointed out in Hewitt et al, U.S. Pat. No. 3,676,199, issued July 11, 1972 and Wixon, U.S. Pat. No. 3,766,062, issued Oct. 16, 1973, many of the prior art softening agents stain or discolor the conditioned fabrics when used in an automatic dryer. The unfortunate tendency of such materials to stain fabrics is apparently caused by the presence of the fatty alkyl groups in the active softening compounds which causes them to be somewhat "greasy". Unevenly distributed fatty softeners can appear as blotchy, oily stains on the treated fabrics. Thus, the chemical structure which gives rise to the soft, lubricious feel associated with the prior art softeners can cause them to be potential fabric stainers.
A variety of mechanical methods have been employed in an attempt to reduce the tendency of dryer-added softeners to stain fabrics. The prior art fabric softening agents, for example, have been sorbed onto flexible articles designed to provide controlled release at dryer operating temperatures. While such articles are quite attractive from the standpoint of ease of manufacture and economics, staining can still be a problem if an improperly formulated flexible article becomes entangled in clothing. Various rigid dispensers and appliances have been designed which assertedly avoid any exceptionally high, localized concentration of softening agent being undesirably deposited on the fabrics in the form of greasy stains (See Hoeflin, U.S. Pat. No. 3,633,538, issued Jan. 11, 1972 and Grand et al, U.S. Pat. No. 3,698,095, issued Oct. 17, 1972). However, such dispensers are costly and have not come into general use.
Certain surfactants have been suggested for obviating the tendency of the prior art softeners to stain fabrics (See the co-pending application of Murphy and Habermehl, Ser. No. 440,932, filed Feb. 8, 1974). This nonstaining aspect is especially important when the common polyester fabrics, which are oleophilic and particularly susceptible to oily staining, are softened in an automatic dryer. However, such surfactants are mainly anionic in nature, and are not suitable for use with the common cationic softeners.
As noted above, many softening compounds have been adapted for use in automatic dryers by fashioning articles which contain a pre-measured amount of the softener. Preferred articles comprise a flexible sheet substrate coated and/or impregnated with an optimal, pre-measured amount of a fabric softener. These articles are simply added to a dryer together with the fabrics to be dried. The heat and tumbling action of the dryer helps dispense the softener onto the fabric surfaces (See for example, Perez-Zamora, U.S. Pat. No. 3,632,396, issued Jan. 4, 1972). However, once sorbed onto the sheet substrate, some softeners tend to remain affixed thereto, rather than being dispensed onto the fabrics. Thus, the user of such articles cannot be assured that the optimal amount of softener is, in fact, deposited on the fabrics. To obviate this problem, it has been suggested to layer the softener onto the sheet together with surfactant-type release agents which insure substantially complete transfer to the fabrics; (See Perez-Zamora, U.S. Pat. No. 3,632,396, issued Jan. 4, 1972). Glycerides are among the materials recognized by Perez-Zamora as being useful as release agents for various types of softeners.
Finally, some cationic materials recognized for use as fabric softeners and anti-static agents in dilute aqueous rinse baths are not particularly useful in certain automatic dryers in that they are reported to soften and loosen certain paints used to protect the dryer drum and to corrode exposed metal surfaces of some automatic dryer drums.
As can be seen from the foregoing, there is considerable interest in providing reduced staining fabric softeners which can be conveniently applied to fabrics in an automatic clothes dryer. Moreover, the difficulty in securing controlled softener release from dispensers is well-recognized by workers in this field. Finally, there is likewise considerable interest in eliminating or minimizing dryer paint softening and corrosion caused by some dryer-added fabric treating products.
By the present invention, lanolin alcohols, or certain esters and propylene oxide adducts thereof are added to cationic fabric softeners to provide particularly useful dryer-added softener compositions and articles. The lanolin alcohols (or specified derivatives thereof) provide auxiliary softening and anti-static treatment of fabrics along with that provided by the cationic softeners. Moreover, the lanolin alcohols and derivatives provide even release of softening compositions from carrier substrates when such substrates provide the means for dispensing the softening compositions herein into automatic dryers, thereby reducing staining problems. Finally, the lanolin alcohols and derivatives reduce the tendency of the cationic softener material to soften paint and corrode metal surfaces in automatic clothes dryers.
Various compounds containing hydroxyl groups are recognized as useful fabric treating agents in aqueous media, e.g., those listed in Speel et al, Textile Chemicals and Auxiliaries, 2nd Edition; Reinhold Publishing Corporation, 1957. Some ethoxylated alcohols are further known to be useful in textile lubricating compositions in combination with quaternary ammonium materials (See Cohen et al, U.S. Pat. No. 3,773,463, issued Nov. 20, 1973).
The use of various glycerides to lubricate and soften textiles is well known in the art. See for example U.S. Pat. No. 3,785,973. Likewise, their use for the treating of fabrics in a laundry with or without the presence of relatively low levels of quaternary ammonium softeners has been disclosed in application Ser. No. 440,931, filed Feb. 8, 1974, U.S. Pat. No. 4,000,340, cited supra. The use of various polyol esters to condition fabrics in a dryer is disclosed in British Pat. No. 1,383,748, published Feb. 12, 1975. The use of fatty sorbitan esters with high levels of quaternary ammonium softeners in dryer-added fabric treatment articles to improve softener release and reduce fabric staining and dryer damage has been disclosed in application Ser. No. 543,607, Zaki, filed Jan. 23, 1975, (now U.S. Pat. No. 4,022,938, issued May 10, 1977) which is a continuation-in-part of Ser. No. 461,312, filed Apr. 16, 1974, now abandoned. Fabric treating compositions comprising glycerides and cationic softeners are disclosed in U.S. Pat. No. 2,735,790, Waitkus, issued Feb. 21, 1956.
U.S. application Ser. No. 647,969, McCarty et al., filed Jan. 9, 1976, discloses the use of polyglycerol esters as fabric softening agents for use in treating fabrics in a dryer.
Belgian Pat. No. 805,887, Liebowitz et al., published Feb. 1, 1973, discloses the use of lanolin and hydrophilic derivatives thereof as fabric softening agents in aerosol compositions for use in the dryer.
U.S. application Ser. No. 647,970, Norris, filed Jan. 9, 1976, discloses the use of fatty acid esters of various polyols as fabric softening agents to be used in combination with quaternary ammonium softeners in softening fabrics in a dryer and thereby reducing the corrosive effect which quaternary softeners have on metal and painted surfaces in the dryer.
The above prior art references do not suggest the formulation of dryer-added fabric softening articles of the type disclosed herein comprising a dryer dispensing means, a cationic softener, and a lanolin fatty alcohol component of the type and in the amounts specified herein, nor do these references suggest the anti-corrosion, anti-paint softening benefits provided by the particular mixture of materials employed herein in automatic laundry dryers.
Accordingly, it is an object herein to provide superior methods and articles of manufacture adapted for imparting softness and anti-static benefits to fabrics in a clothes dryer.
It is another object herein to provide such fabric softening articles which are easily manufactured on a commercial scale.
It is another object herein to provide dryer fabric softening articles and methods which do not disadvantageously promote softening of dryer drum paint or corrosion of exposed metal dryer drum surfaces.
These and other objects are obtained herein as will be seen from the following disclosure.